Musical sounds and events are indicative and reflective of human culture's perception, understanding, and production of sound, language, and meaning. Music is generally performed based on human intention by the actions of the body and also the manipulation of musical instruments, and considered a form of artistic expression. Musical instruments have evolved along with technology. Musical compositions, performances, and events may be predetermined to the extent possible by human intention (musical composition) or left to be partially or completely improvised based on human-provided structures (Indian Ragas, Jazz). Other independent sources of musical sound have also long been recognized, either from natural or animal sounds (birds singing, water moving among rocks, wind moving among structures) or environmentally stimulated musical devices produced by human ingenuity (wind chimes, Aeol's harp).
In some forms of music, acoustical and natural laws provide structure (scales, chords) but in other forms of music (mostly electronic) more general acoustic phenomena and structures (atonality, serialized tones and rhythm, noise spectra, and sound events in an environment) may be recognized as musical.
Music is mainly performed by trained artists, but sometimes the “audience” also participates in a musical event (clapping, cheering, singing along, etc.).
Human artistic determination of music (composition, improvisation) is generally accepted, but random generation and machine or computer determination are also used to alter or create musical events.